Low-frequency electric and magnetic fields (greater than 0 Hz to 100 kHz) are primarily caused by industrial applications. Each electric conductor in which current flows is surrounded by a magnetic field and an electric field. Of everyday importance are mainly the electric and magnetic fields which are produced by the power supply (50 Hz) and electrified traffic systems such as railways (16 ⅔ Hz). Because of their physical characteristics, electric and magnetic fields are present in decoupled form in the low-frequency range.
High-frequency electromagnetic fields (>100 kHz-300 GHz) (HF-EMF) in our everyday life primarily occur in applications which are used for wire-free information transmission in broadcasting, television, mobile radio and other communication technologies. Other important areas of application are medicine and numerous industrial processes. In HF-EMF, the electric and magnetic components are very closely coupled with one another at a distance from the source that depends on the wavelength. In the case of very short wavelengths, it is therefore barely possible to attribute effects and actions which, for example, occur when they strike the human body, to the action of only one of the two components.
The higher and higher power of batteries required recently and also in the future, in particular in the motor vehicle sector, leads to these batteries, owing to their electromagnetic fields, increasingly being able to exert an influence on the on-board electronics of vehicles, in particular motor vehicles, or being able to exert an influence on the wire-free transmission of information, and being able to quite considerably disrupt those on-board electronics or information transmission electronics. Other areas of application such as medical appliances or telecommunication or navigation devices can also be affected.
JP 2004-082141 A discloses an injection-moulded structural component for screening electromagnetic fields (EMF), for example for use as a housing part for batteries in motor vehicles, composed of a thermoplastic material, namely polypropylene, which has a high electrical conductivity as a result of the addition of metal fibres.
JP 2005-264097 A describes an injection-moulded article composed of a coated resin composition made of metal fibres A, a fibrous or cylindrical metal B with a lower melting point than A without any lead being present therein, and a thermoplastic resin C.
The object of the present invention was to elaborate a concept for an EMF-screened structural component which is able both to screen an electro-technical component with respect to external EMF and also to damp the EMF emitted by this component, without having to accept any losses in terms of the mechanical properties.
However, since each structural component has to simultaneously take into account the weight restrictions required in current automobile construction, the lightest possible construction of the same is required.